Effect of molecular weight, temperature, and pH on antioxidant activity of whey protein isolate hydrolysate and its application in pasta fortification

This study explored the enzymatic hydrolysis of whey protein concentrate (WPC) and isolate (WPI), and evaluated the antioxidant, physicochemical, textural, and sensory properties of pasta fortified with whey protein hydrolysate (WPH). WPI hydrolysate (WPIH) exhibited higher antioxidant activity than WPC hydrolysate (WPCH), with DPPH and ABTS⁺ radical scavenging activity (RSA) values of 6 and 211 µmol Trolox/g dry weight, respectively, at 5% enzyme to substrate (E/S). Fractionation of WPIH revealed that peptides lower than 2 KDa (F1) had the highest ABTS⁺ RSA (237 µmol Trolox/g), while peptides higher than 10 KDa (F3) showed the greatest DPPH RSA (6 µmol Trolox/g) and Fe²⁺ chelating capacity (13 µmol EDTA/g). Antioxidant stability was highest at pH 5 and 60 °C. Incorporation of 0.5–1.5 g/100 g WPIH into pasta significantly enhanced antioxidant properties, increasing DPPH RSA from 0.89 to 2 µmol Trolox/g, ABTS⁺ RSA from 136 to 463 µmol Trolox/g, and Fe²⁺ chelation from 6.8 to 8.5 µmol EDTA/g. Fortified pasta also showed higher protein, reduced cooking time, increased cooking loss, and decreased hardness. Sensory evaluation indicated acceptable quality up to 1 g/100 g WPIH, beyond which texture and aroma declined. These findings suggest that WPIH can be used as a functional component in pasta to increase nutritional value and antioxidant capacity at modest inclusion levels without lowering consumer acceptability.